Former NASA Official Says Crewed Mars Flyby is Feasible by 2021
SpaceNews

A crewed Mars flyby mission proposed last year by space tourism pioneer Dennis Tito could conceivably launch in 2021 provided that NASA immediately begins spending money on a large new upper-stage rocket engine and crew-habitation module that currently are not on the agency’s development plate, a former NASA official told lawmakers Feb. 26.
“I believe that 2021 is possible if the focus is placed on getting that mission on our books,” Doug Cooke, former associate administrator of NASA’s Exploration Systems Mission Directorate and now a private consultant, said during a hearing of the House Science Committee. “It would take a commitment to develop the full upper stage in the timeframe that we’re talking about. We would [also] need a small [habitation module], perhaps using an existing structure.”
The mission, which was the subject of the hearing, was originally proposed by a Tito-led group calling itself Inspiration Mars, in early 2013 as a privately funded venture. It was subsequently reformulated to take advantage of the Space Launch System (SLS) rocket and Orion Crew capsule NASA is developing.